This process is referred to as timebase correction and as stated before, any quality piece of equipment will implement it.

That has been the ritual answer to jitter concerns since I'm on the Internet.

But... if "any quality piece of equipment will implement it", then some non-quality pieces of equipment don't implement it. My question is : which ones ?

The statement "quality piece of equipment" is completely subjective and doesn't give any information. For my grandfather, a "quality" CD reader will be a portable radio-cassette-CD-speakers combo for 100 $ in the supermarket. The "non-quality" one will be the Fisher-Price toy for children from 3 to 7.For an audiophile friend, the "quality" CD player will be the 25,000 $ Wadia CD Transport+DAC, while any player under 1,500 $ is just worthless crap.

So, do a 200 $ CD Player always have a RAM buffer ? Or is it not considered a quality piece of equipment ? What about a 300 $ CD Player from 1990 ?

There is a device available from most high-end audio shops to correct jitter created by clocking differences between devices. I think it's called a Monarch DIP (Digital Processor).

Couldn't find any references to it on the web, except for an auction. How does it work? Assuming the input is SPDIF, and the output is likewise, I'm curious as to how it doesn't just create a new jittery SPDIF stream. If it's a different beast, my apologies in advance...